The present invention relates to a vein compressing/blocking device and, particularly, to a vein compressing device for application to the upper arm of a patient during blood drawing processes.
Among other things, the drawing of blood belongs to the routine work of doctors in hospitals and practices. In order to compress the veins of the upper arm of a patient for this, a venous compression tube is used. This is a flexible belt having a small clasp. This known compression tube is wound around the upper arm of a patient and tightened, which causes the veins to be squeezed off and the blood contained therein to be compressed. This, in turn, causes a bulging (swelling) of the veins, which allows the doctor to insert a cannula for drawing blood in a more precise way and, thus, to draw the blood.
However, this method is disadvantageous insofar as an attending doctor does not have any control over the amount of pressure at which the compression tube acts on the upper arm in dependence on the tensile force in the compression tube. This disadvantage is further increased by the conventional compression tubes being made of flexible material, which expands when certain tensile forces act thereon and, thus, gives the doctor an extremely xe2x80x9cspongyxe2x80x9d feeling of force.
Due to these insecurities of control, it often happens that not only the veins but also the lower-lying arteries of the patient to be treated are squeezed off, so that, in this case, an effect of an overfilling of the veins, which makes the veins visible, is no longer possible.
In view of this prior art, it is the object of the invention to create a vein compressing device, for example, used for drawing blood, which can be operated more exactly in order to guarantee the effect of the overfilling of the veins.
The aforementioned problems are solved by a vein compressing device comprising a pressure hose cuff having a pressure source connected thereto and a pressure adjusting auxiliary means, by means of which the inner pressure in the cuff can be detected and/or adjusted to a predetermined value. This value corresponds to a pressure causing a squeezing off of a vein, but simultaneously maintaining the flow cross-section of an artery at least partly. In this way, a blood flow in the artery can be maintained, so that the squeezed-off vein is gradually inflated by the blood compressed therein and, as a result, becomes better visible to the doctor. The predetermined pressure value has either been determined in advance by tests for different patients (age, physical constitution, different muscular systems, etc.) and stored in a table, or is calculated anew when the blood pressure is read.
Different appliances are suited for the formation of the pressure adjusting auxiliary means.
According to claim 2, a manually or electronically adjustable pressure relief valve is provided for this purpose, the pressure relief valve being disposed on the pressure hose cuff or on the pressure source. This embodiment has the advantage that no substantial technical measures have to be taken to exclude that a predetermined value is exceeded.
As an alternative, claim 1 provides that the pressure adjusting auxiliary means is formed with a pressure sensor which is connected to a microcomputer on which the predetermined value is adjusted. This embodiment facilitates the handling of the device and ensures a more exact adjustment of the inner pressure of the cuff by the feedback control process between the pressure sensor, the microcomputer, and the pressure source.
According to claim 6, a simple design of the pressure adjusting auxiliary means provides the arrangement of a simple pressure display signaling visually or acoustically that the predetermined value is reached.
Further advantageous developments of the invention are set out in the remaining claims.